PRIOR CONCURRENT THERAPY: Biologic therapy: Recovered from prior immunotherapy No concurrent prophylactic colony-stimulating factors (e.g., filgrastim (G- CSF) or sargramostim (GM-CSF)) during first course of study No concurrent anticancer immunotherapy Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) and recovered No other concurrent chemotherapy Endocrine therapy: No concurrent anticancer hormonal therapy Radiotherapy: See Disease Characteristics Recovered from radiotherapy No concurrent radiotherapy except palliative local radiotherapy Surgery: See Disease Characteristics Other: At least 30 days since prior investigational drugs No other concurrent investigational or experimental anticancer drugs No concurrent participation in other clinical trial